JP2019077890A - Copper alloy for electronic material - Google Patents

Abstract

To provide a copper alloy for electronic material having suitable 0.2% bearing force, conductivity and flexure processability, and suppressed spring back during flexure processing and high in credibility, when used in an electronic material.SOLUTION: The copper alloy for electronic material contains 0.5 to 3.0 mass% of Co and Si with Co/Si by mass ratio of 3 to 5, and the balance copper with inevitable impurities, and satisfying a relationship of S=S/(S+S)≥0.5, wherein integration degree of crystal orientations of box numbers 1, 21, 36 obtained by conducting equal area division used by a display by a vector method on a stereo triangle representing crystal orientations of a rolling parallel direction (RD) obtained by an EBSD (Electron Back Scatter Diffraction) measurement are S, S, and Srespectively.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a Cu--Co--Si alloy which is a precipitation-hardened copper alloy suitable for use in various electronic parts, and in particular, proposes a technique capable of improving the dimensional accuracy during bending. It is

  Copper alloys for electronic materials used in various electronic components such as connectors, switches, relays, pins, terminals, lead frames etc. are required to have both high strength and high conductivity (or thermal conductivity) as basic characteristics Be done. And, in recent years, high integration, miniaturization, and thinning of electronic parts have rapidly progressed, and the requirements for copper alloys used for electronic parts have been further advanced along with this. In particular, in order not to enlarge the connector, a 0.2% proof stress in the parallel rolling direction of 550 MPa or more and a conductivity of 55% IACS or more are desired.

  From the viewpoint of high strength and high conductivity, the amount of use of the precipitation hardening copper alloy is increasing instead of the conventional solid solution strengthened copper alloy represented by phosphor bronze, brass and the like as a copper alloy for electronic materials . In the precipitation hardening type copper alloy, when the solution-processed supersaturated solid solution is subjected to an aging treatment, the fine precipitates are dispersed uniformly, and the strength of the alloy becomes high, and at the same time, the amount of solid solution elements in copper decreases. Electrical conductivity is improved. For this reason, it is possible to obtain a material which is excellent in mechanical properties such as spring property and is also excellent in electrical conductivity and thermal conductivity.

Among precipitation-hardened copper alloys, Cu-Ni-Si alloys generally referred to as corson alloys are representative copper alloys having relatively high conductivity, strength, and bending workability, and are currently used in the art. It is one of the alloys under active development. In this copper alloy, strength and conductivity can be improved by precipitating fine Ni-Si based intermetallic compound particles in a copper matrix.
In such Corson alloys, Cu-Co-Si alloys in which Ni is replaced by Co have been proposed for the purpose of further improving the properties.

  The Cu-Co-Si type alloy is related to general bending workability, and patent documents 1 and 2 describe the art which controls crystal orientation with a Cu-Co-Si type alloy.

  Specifically, in Patent Document 1, in crystal orientation analysis in EBSD (Electron Back-Scatter Diffraction: electron backscattering diffraction) measurement, the area ratio of Brass orientation {110} <112> is 20% or less, Copper orientation {121 Area ratio of <111> is 20% or less, area ratio of Cube orientation {001} <100> is 5 to 60%, 0.2% proof stress is 500 MPa or more, conductivity is 30% IACS or more A copper alloy material is described which is characterized by Patent Document 2 also describes a copper alloy sheet material characterized in that the area ratio of cube orientation {001} <100> is 7 to 47% in crystal orientation analysis in EBSD measurement, and further, S orientation {231 The copper alloy sheet material whose area ratio of <346> is 5 to 40% is described.

JP, 2011-017072, A Patent 4875768 gazette

  However, although the copper alloy sheet materials according to Patent Documents 1 and 2 are excellent in bending workability, it is considered that there is still an insufficient point in spring back at the time of bending. Springback is a phenomenon in which deformation of the material is slightly restored when the forming tool is released from the material in bending. Springback adversely affects the dimensional accuracy of the finished part.

  The copper alloy sheet materials according to Patent Documents 1 and 2 develop Cube orientation {001} <100> to improve bending workability, but Young's modulus of a material having Cube orientation {001} <100> developed Tend to decrease. On the other hand, since the amount of springback is proportional to the yield stress of the material and inversely proportional to the Young's modulus, springback becomes large if Cube orientation {001} <100> is developed.

Thus, the copper alloy sheet material which concerns on patent document 1 and 2 was not enough as the dimensional accuracy of the finished components by the spring back at the time of bending.
As a measure against spring back, there is a method of forming a V-notch in a bent portion before bending the alloy, but inevitably the strength of the bent portion is reduced and a crack is easily generated.

  An object of the present invention is to solve such a problem, and the object is to have 0.2% proof stress, conductivity and bending workability suitable for use in electronic materials, and at the time of bending It is an object of the present invention to provide a highly reliable copper alloy for electronic materials in which the springback in the above is suppressed.

  As a result of intensive studies, the inventor of the present invention has found that, in a Cu-Co-Si alloy, stereo triangles representing crystal orientations in the rolling parallel direction are subjected to equal area division used in vector method display and obtained at predetermined positions. It has been found that by controlling the degree of integration of crystal orientation, it is possible to suppress springback during bending. And, it was found that such control of the degree of accumulation of crystal orientation can be realized by adjusting processing conditions such as homogenization annealing, hot rolling and solution treatment.

Under the above findings, the present invention contains 0.5 to 3.0% by mass of Co, and contains Si in a mass ratio such that Co / Si is 3 to 5 with the balance being copper and unavoidable Performs equal area division used in vector method display on stereo triangles representing crystal orientations in the rolling parallel direction (RD) obtained from chemical impurities and obtained from EBSD (Electron Back Scatter Diffraction) measurement. When the degree of integration of the crystal orientations of box numbers ₁ , ₂₁ and ₃₆ obtained as above is S ₁ , S ₂₁ and S ₃₆ respectively,
S = S ₂₁ / (S ₁ + S ₃₆ ) ≧ 0.5
It is a copper alloy for electronic materials which satisfies the relationship of

  The copper alloy for electronic materials of the present invention has an actual bending deformation angle of θ (° in the central portion among the three portions in a bending test piece) in a 90 ° W bending test according to JIS H 3130 (2012). When it is referred to as), it is preferable that the value of (theta) -90 degrees which shows spring back amount (DELTA) (theta) is 5 degrees or less.

  The copper alloy for electronic materials of the present invention is, according to JIS H 3130 (2012), in a 90 ° W bending test, JIS B 0601 (2013) on the outer peripheral surface of the bent portion (central portion among three points) in the bending test piece The compliant surface average roughness Ra is preferably 1.0 μm or less.

  The copper alloy for electronic materials of the present invention preferably further contains Cr at 0.5% by mass or less.

  The copper alloy for electronic materials of the present invention further contains Zn and Sn at 0.5 mass% or less, Ni at 0.1 mass% or less, Mg, Mn, Fe, Ti, Al, P and B at 0.2. It is preferable that the total content of at least one or more selected from Zn, Sn, Ni, Mg, Mn, Fe, Ti, Al, P, and B be 1.0% by mass or less. .

  Furthermore, the present invention also provides an electronic component comprising the copper alloy for electronic materials of the present invention.

  According to the present invention, it is possible to provide a highly reliable copper alloy for electronic materials which has suitable 0.2% proof stress, conductivity and bending workability and which suppresses springback during bending.

FIG. 1 shows a stereographic projection display of angles of rotation of the Williams method and the vector method representing crystal orientation. FIG. 2 shows stereo triangles divided into 36 by equal area division.

Hereinafter, embodiments of the present invention will be described in detail.
The copper alloy for electronic materials according to one embodiment of the present invention contains 0.5 to 3.0% by mass of Co, and contains Si in a mass ratio of 3 to 5 of Co / Si, Used in vector method display for stereo triangles that represent the crystal orientation in the rolling parallel direction (RD) obtained from EBSD (Electron Back Scatter Diffraction) measurement, with the balance being copper and unavoidable impurities Assuming that the degree of integration of crystal orientations of box numbers ₁ , ₂₁ and ₃₆ obtained by performing equal area division is S ₁ , S ₂₁ and S ₃₆ respectively,
S = S ₂₁ / (S ₁ + S ₃₆ ) ≧ 0.5
Meet the relationship.

(Co addition amount)
Co and Si are precipitated in the matrix as Co ₂ Si by performing appropriate heat treatment, and high strength can be achieved without deteriorating the conductivity. However, when the Co concentration is less than 0.5% by mass, precipitation hardening is insufficient, and even if the other component is added, the desired strength can not be obtained. When the Co concentration exceeds 3.0% by mass, sufficient strength can be obtained, but the conductivity, bending workability, and hot workability are reduced.
Preferably, it is 1.0 to 2.5% by mass of Co.

(Addition amount of Si)
Si is adjusted so that Co / Si becomes 3 to 5 in mass ratio. With the ratio, it is possible to improve both the strength and the conductivity after precipitation hardening. When the ratio exceeds 5, precipitation of Co ₂ Si in the aging treatment becomes insufficient, and the strength decreases. If the ratio is less than 3, Si that does not precipitate as Co ₂ Si forms a solid solution in the matrix phase, and the conductivity decreases.

(Cr addition amount)
Cr preferentially precipitates on grain boundaries in the cooling process at the time of melt casting, so that the grain boundaries can be strengthened, cracking at the time of hot working becomes difficult to occur, and yield loss can be suppressed. That is, although Cr precipitated at grain boundaries during melt casting re-dissolves by solution treatment or the like, during subsequent aging precipitation, it forms a compound with precipitated particles of bcc structure mainly composed of Cr or Si. In the usual Cu-Co-Si alloy, Si, which did not contribute to the aging precipitation, among the amount of Si added, suppresses the increase in conductivity while remaining in solid solution in the matrix, but Cr which is a silicide forming element By further depositing the silicide, the amount of solid solution Si can be reduced, and the conductivity can be increased without losing the strength. However, if the Cr concentration exceeds 0.5% by mass, coarse second phase particles are likely to be formed, which impairs product properties. Therefore, in the present invention, Cr can be added at a maximum of 0.5% by mass. However, if the amount is less than 0.03% by mass, the effect is small, so it is preferable to add 0.03 to 0.5% by mass, more preferably 0.09 to 0.3% by mass.

(Addition amount of Sn and Zn)
Also in Sn and Zn, the addition of a small amount improves the product characteristics such as strength, stress relaxation characteristics and plating property without losing the conductivity. The effect of the addition is mainly exhibited by solid solution in the matrix phase. However, if each concentration of Sn and Zn exceeds 0.5% by mass, the property improvement effect is saturated and the productivity is impaired. In addition, the desired orientation can not be obtained in the product, and the bending processability is reduced. Therefore, in the present invention, each of Sn and Zn can be added up to 0.5% by mass. However, since the effect is small when the total of Sn and Zn is less than 0.05% by mass, the total of Sn and Zn is preferably 0.05 to 0.5% by mass, more preferably 0.1 to 0.5. It can be mass%.

(Ni addition amount)
Ni can be added as it is precipitated in the matrix as Ni ₂ Si by appropriate heat treatment to improve the strength of the alloy. However, when the concentration of Ni exceeds 0.1% by mass, the conductivity is impaired, so the addition amount of Ni is preferably 0.02 to 0.1% by mass.

(Addition amounts of Mg, Mn, Fe, Ti, Al, P and B)
Mg, Mn, Fe, Ti, and Al, when added in small amounts, improve product characteristics such as strength and stress relaxation characteristics without losing conductivity. P has a deoxidizing effect, B has a refining effect on the cast structure, and has an effect to improve the hot workability. The effect of the addition is exhibited mainly by solid solution in the matrix phase, but it is possible to exhibit further effects by being contained in the second phase particles. However, if the concentration of each of Mg, Mn, Fe, Ti, Al, P and B exceeds 0.2% by mass, the property improvement effect is saturated and the productivity is impaired. Therefore, in the present invention, Mg, Mn, Fe, Ti, Al, P and B can be added up to 0.2 mass% at the maximum. However, if the sum of Mg, Mn, Fe, Ti, Al, P and B is less than 0.01% by mass, the effect is small, so the sum of Mg, Mn, Fe, Ti, Al, P and B is preferably It can be 0.01 to 0.2% by mass, more preferably 0.04 to 0.2% by mass.

  When it contains Zn, Sn, Ni, Mg, Mn, Fe, Ti, Al, P and B mentioned above, it is selected from those Zn, Sn, Ni, Mg, Mn, Fe, Ti, Al, P and B The total of at least one or more of them is 1.0% by mass or less. If this total exceeds 1.0% by mass, the conductivity decreases. In addition, the desired orientation can not be obtained in the product, and the bending processability is reduced.

(0.2% proof stress)
In order to satisfy the characteristics required for a predetermined electronic material such as a connector, the 0.2% proof stress in the rolling parallel direction is preferably 550 MPa or more, more preferably 580 MPa or more. The upper limit value of the 0.2% proof stress is not particularly limited, but is typically 800 MPa or less to achieve a conductivity of 55% IACS or more.
0.2% proof stress is measured according to JIS Z2241 using a tensile tester.

(conductivity)
Conductivity shall be 55% IACS or more. Thereby, it can be effectively used as an electronic material. The conductivity can be measured by the four-terminal method in accordance with JIS H0505. The conductivity is preferably 60% IACS or more.

(The degree of accumulation of crystal orientation)
The degree of integration of the crystal orientations of box numbers 1, 21 and 36 obtained by performing equal area division used in the vector method display on stereo triangles representing crystal orientations in the rolling parallel direction (RD) is S ₁ , S ₂₁ and S ₃₆ ,
S = S ₂₁ / (S ₁ + S ₃₆ ) ≧ 0.5
If the following condition is satisfied, bending workability is improved, and spring back at the time of bending can be effectively suppressed.
Here, S ₁ is <001> direction, S ₂₁ is <211> direction, S ₃₆ corresponds to the <111> direction of integration.
The reason is not necessarily clear and is only an estimate, but the Schmid factor representing the ease of plastic deformation of the crystal is 0.41 in S ₂₁ : <211> and in the S ₃₆ : <111> direction. since it is 0.27, reducing the degree of integration of small S ₃₆ of the Schmid factor, by increasing the degree of integration of a large S ₂₁ of Schmid factor is considered possible to improve the bending workability. The S _1: <001> is to increase according to the accumulation of Cube orientation {001} <100> to bring an adverse effect on the spring-back is believed to be reduce spring back by reducing the degree of integration S _1.
From this viewpoint, S is preferably 1.0 or more, more preferably 2.0 or more.
The degree of integration of crystal orientation is obtained from EBSD (Electron Back Scatter Diffraction) measurement.
FIG. 1 is a stereographic projection display of the rotation angle of the vector method (two-axis pole figure method) representing the crystal orientation of a copper alloy. In FIG. 1, a point RD representing the rolling parallel direction (RD) of the surface of the copper alloy plate is indicated by coordinates (ψ, λ) on the stereo triangle (T1) on which it is mounted. It is FIG. 2 which divided this stereo triangle into 36 by equal area division (by Ruer et al.). Among the crystal orientations in the stereo triangle of FIG. 2, the crystal orientation in the region indicated by the number 1 is “the crystal orientation of the box number 1” (Furubayashi, “Recrystallization and material structure”, 1st edition, Uchida Tsurushima, pages 88-89). Further, “the degree of integration of crystal orientation of box No. 1” represents the average intensity of the section on the pole figure represented by the orientation corresponding to box No. 1. The crystal orientations of box numbers 21 and 36 are similarly defined.

(Springback amount Δθ)
The small amount of springback Δθ is a manifestation of effective suppression of springback at the time of bending. From this viewpoint, the amount of springback Δθ is 5 ° or less, preferably 4.0 ° or less, and more preferably 3.5 ° or less.
The amount of springback Δθ is θ (°) when the actual bending deformation angle of the bending portion (central portion among the three portions) in the bending test piece is 90 ° W bending test based on JIS H 3130 (2012) And θ-90 ° can be measured.

(Bent part outer peripheral surface roughness Ra)
Since there is a phenomenon that small irregularities on the surface of the material start to grow into cracks, if the roughness Ra of the outer peripheral surface of the bent portion is small, it is difficult to grow into cracks and it is easy to bend. From this viewpoint, the roughness Ra of the outer periphery of the bent portion is 1.0 μm or less, preferably 0.8 μm or less, and more preferably 0.6 μm or less.
In the 90 ° W bending test according to JIS H 3 130 (2012), the outer peripheral surface roughness Ra of the bent portion is JIS B 0601 (2013) on the outer peripheral surface of the bent portion (central portion among three points) in the bending test piece. It can be measured in accordance with

(Production method)
The Cu-Co-Si alloy as described above is manufactured by sequentially performing an ingot manufacturing process, a homogenizing annealing process, a hot rolling process, a solution treatment process, an aging process, and a final cold rolling process. can do. In addition, after hot rolling, it is possible to carry out facing as needed.

  Specifically, first, a raw material such as electric copper, Co, Si or the like is melted using an atmospheric melting furnace or the like to obtain a molten metal having a desired composition. Then, the molten metal is cast into an ingot. Thereafter, hot rolling is performed, and solution treatment, aging treatment (1 to 24 h at 450 to 550 ° C.), and final cold rolling (processing degree 10 to 50%) are performed. After the final cold rolling, strain relief annealing may be performed. The strain relief annealing can be performed usually at 400 to 600 ° C. for 0.5 to 5 minutes in an inert atmosphere such as Ar. After the solution treatment, cold rolling and aging treatment may be performed in this order.

Here, in this production method, it is important to perform homogenization annealing, hot rolling and solution treatment under predetermined conditions after the ingot production. In the prior art, the conditions of these steps were not optimized, the characteristics as in the present invention could not be obtained, and in particular, springback could not be suppressed significantly.
In the following, the respective steps of the homogenization annealing, hot rolling and solution treatment will be described in detail. In addition, it is possible to set it as the conditions normally employ | adopted in the manufacturing process of a Cu-Co-Si type | system | group alloy in another process.

<Ingot production>
Melting casting is generally carried out in an atmospheric melting furnace, but can also be carried out in vacuum or in an inert gas atmosphere. After the electric copper is melted, the raw materials are added according to the composition of each sample such as Co, Si, etc., and after stirring it is held for a fixed time to obtain a molten metal having a desired composition. And after adjusting this molten metal to 1250 degreeC or more, it casts to an ingot. In addition to Co and Si, 0.5 mass% or less of Cr, at least one or more selected from Zn, Sn, Ni, Mg, Mn, Fe, Ti, Al, P, and B to a total of 1.0 mass% or less It can also be added to

<Homogenization annealing>
By performing the homogenization annealing at an appropriate temperature and time, coarse Co-Si particles generated at the time of casting can be dissolved in the matrix and the stacking fault energy can be made low. Since materials with low stacking fault energy are difficult to cross-slip, dynamic recovery is less likely to occur and dislocations are likely to be accumulated. In the subsequent hot rolling, dynamic recrystallization occurs with the accumulated dislocations as a driving force to refine the crystal grains. In order to obtain the desired degree of accumulation of crystal orientation (S ₂₁ / (S ₁ + S ₃₆ ) ≧ 0.5) in a product, it is preferable that the grain size at the end of the hot rolling be smaller. If the temperature of homogenization annealing is too high, the material may be melted, and dynamic recrystallization proceeds too much, resulting in coarse grains at the end of hot rolling, and accumulation of the desired crystal orientation in the product. I can not get a degree. When the temperature of the homogenization annealing is too low, coarse Co-Si particles can not be solid-solved in the matrix, and a desired orientation can not be obtained in the product. Specifically, the homogenization temperature is preferably 950 to 1025 ° C., and the time is preferably 1 to 24 h.

<Hot rolling>
The ingot after completion of the homogenization annealing is extracted from the furnace and subjected to hot rolling. By increasing the rolling strain rate ε (sec ^-1 ) in the final pass of hot rolling, strong processing can be performed with higher energy, and the grain size at the end of hot rolling is reduced by dynamic recrystallization. be able to. Here, the rolling strain rate ε is expressed by the following equation.
In the formula, n: roll rotational speed (rpm), r: rolling reduction, R: roll radius (mm), H ₀ : entrance side plate thickness (mm). If the strain rate ε is too small, grain refinement at the end of hot rolling becomes insufficient, and the desired degree of accumulation of crystal orientation can not be obtained in the product. If the strain rate ε is too large, the load on the rolling mill will be too large to be realistic. Specifically, the strain rate is 30 to 60 sec ^-1 , preferably 40 to 60 sec ^-1 .
In addition, it is desirable to quickly cool after hot rolling. When the cooling rate is slow, coarse Co-Si particles are precipitated. When a large number of coarse Co-Si particles are present, they can not be sufficiently dissolved in solution treatment, and a predetermined strength can not be obtained in the product. In addition, the degree of integration of the orientation corresponding to the box No. 21 is not sufficiently developed, and the bending workability is reduced. Since the precipitation temperature range of this compound is 400 ° C. or more, this precipitation can be suppressed by quenching (eg, water cooling) to 400 ° C. or less after the completion of the hot rolling. Specifically, the cooling rate to 400 ° C. is 15 ° C./sec or more, preferably 20 ° C./sec or more.

<Solution treatment>
The purpose of the solution treatment is to cause Co-Si particles precipitated during hot rolling to form a solid solution and to enhance the age hardenability after the solution treatment. If the temperature of the solution treatment is too low, these precipitates can not be sufficiently dissolved, and a predetermined strength can not be obtained. Further, the degree of integration of the orientation corresponding to the box No. 21 is not sufficiently developed, and the bending workability is lowered. When the temperature of the solution treatment is too high, the pinning effect of the grain boundaries by the precipitates disappears, and the crystal grains are coarsened to lower the strength. Further, the degree of integration of the orientation corresponding to the box No. 1 is increased, and the springback at the time of bending is increased. As a temperature of the solution treatment, it is preferable to heat the copper alloy material before the solution treatment to a temperature near the solid solubility limit of the second phase particle composition. Specifically, the heating is performed at 850 to 1000 ° C. for 0.5 to 10 minutes. Moreover, from the viewpoint of preventing precipitation of second phase particles and coarsening of recrystallized grains, it is preferable that the cooling rate after the solution treatment be as high as possible. Specifically, the average cooling rate when the material temperature decreases from the solution treatment temperature to 400 ° C. is preferably 15 ° C./sec or more, and more preferably 50 ° C./sec or more.

<Aging treatment>
Subsequent to the solution treatment, the desired strength and conductivity can be obtained by performing an aging treatment so that precipitates of appropriate size are uniformly distributed. The temperature of the aging treatment is preferably 450 to 550 ° C. because the conductivity is lower when the temperature is lower than 450 ° C. and the strength is lowered when the temperature is higher than 550 ° C. Moreover, as for the time of an aging treatment, 1 to 24 h is preferable. The aging treatment is preferably performed in an inert atmosphere of Ar, N ₂ , H ₂ or the like in order to suppress the generation of an oxide film.

<Final cold rolling>
By performing final cold rolling after the aging treatment, dislocations are introduced to increase strength. A material with high strength can be obtained as the degree of rolling processing is higher, but if the degree of rolling processing is too high, the proportion of crystal grains in which shear bands are present will increase and the bending workability will deteriorate. Therefore, in order to obtain a good balance of strength and bending workability, the final degree of cold rolling is set to 10 to 50%, preferably 20 to 40%.

<Strain relief annealing>
Subsequent to final cold rolling, stress relief annealing can remove the residual stress generated in the material during processing, and improves the springability. If the holding temperature of strain relief annealing is too high, and if the holding time is too long, coarse Co-Si particles are precipitated to cause a reduction in strength. The holding temperature is 400 to 600 ° C., preferably 450 to 550 ° C. The holding time is 0.5 to 5 minutes, preferably 1 to 3 minutes.

  In addition, processes such as grinding, polishing, shot blasting and pickling for removing oxide scale on the surface can be appropriately performed between the above respective processes.

  The Cu-Co-Si alloy of the present invention can be processed into various copper products such as plates, strips, tubes, rods and wires, and further, the Cu-Co-Si copper alloy has a lead frame, It can be used for electronic components such as connectors, pins, terminals, relays, switches, and foils for secondary batteries. In particular, high dimensional accuracy can be obtained at the time of pressing when manufacturing the connector.

  Next, since the copper alloy for electronic materials of this invention was made as an experiment and the performance was confirmed, it demonstrates below. However, the description herein is for the purpose of illustration only and is not intended to be limiting.

The copper alloy having the component composition shown in Table 1 was melted at 1300 ° C. using a high frequency melting furnace, and cast into a 30 mm thick ingot. Then, the ingot was homogenized under the conditions shown in Table 1, and then hot rolled to a plate thickness of 10 mm at a rolling strain rate shown in Table 1, and the hot rolling end temperature was 900 ° C. After completion of the hot rolling, the material was water cooled at an average cooling rate shown in Table 1 until the material temperature reached 400 ° C., and then left in air for cooling. Then, after surface finishing to a thickness of 9 mm to remove scale on the surface, cold rolling is performed, solution treatment is performed under the conditions shown in Table 1, and then aging treatment is performed at 500 ° C. for 12 hours. It was made into a plate of 0.1 mm in thickness by cold rolling. Finally, strain relief annealing was performed at 500 ° C. for 1 minute.
The following characteristic evaluation was performed to each test piece obtained in this way. The results are shown in Table 2.

<Strength (0.2% proof stress)>
Each test piece was subjected to a tensile test in the rolling parallel direction based on JIS Z2241 to measure a 0.2% proof stress (YS: MPa).

<Conductivity>
The conductivity (EC:% IACS) was determined by volume resistivity measurement using a double bridge in accordance with JIS H0505.

<The degree of accumulation of crystal orientation>
The degree of integration of crystal orientation was evaluated using EBSD (Electron Back Scatter Diffraction) measurement. First, a test piece was cut into a 20 mm square, and the rolled surface was electropolished at a voltage of 15 V for 60 seconds in a 67% phosphoric acid + 10% sulfuric acid solution to reveal a texture. For measurement, JXA8500F manufactured by Nippon Denshi Co., Ltd. is used, the normal direction of the rolling surface of the test piece (ND: Normal Direction) is inclined 70 ° to the incident electron beam, and the rolling parallel direction (RD: Rolling Direction) is It was installed according to the inclination direction, and the focused electron beam was irradiated to the inclined surface. Acceleration voltage: 15.0 kV, irradiation current amount: 5 × 10 ^-8 A, working distance: 15 mm, measurement is performed with n = 5 in the observation field of view 500 μm × 500 μm (step width 1 μm), and the average value is calculated It was a measured value. The measurement program used TSL OIM data collection, and the analysis program used TSL OIM Analysis. Accumulation of crystal orientations of box Nos. 1, 21 and 36 obtained by performing equal area division used in vector method display on stereo triangles obtained when imaging reverse pole figures from parallel rolling directions (RD) degrees to the S _1, S _21, S _36, respectively, to evaluate the value of _{S = S 21 / (S 1} + S 36).

<Bending workability (surface average roughness Ra after bending)>
Conduct the W bending test according to JIS H 3130 (2012) with Goodway (the bending axis is orthogonal to the rolling direction), R / t = 1.0 (t = 0.1 mm), and observe the outer peripheral surface of the bent part of this test piece did. As an observation method, the outer peripheral surface of the bent portion was photographed using a confocal microscope HD100 manufactured by Lasertec Corporation, and the average roughness Ra (based on JIS B 0601 (2013)) was measured and compared using the attached software. In addition, when the sample surface before bending was observed using a confocal microscope, the unevenness | corrugation was not able to be confirmed, but average roughness Ra was 0.2 micrometer or less in all.
The case where the surface average roughness Ra after bending was 1.0 μm or less was evaluated as ○, and the case where Ra exceeded 1.0 μm was evaluated as x.

<Springback angle Δθ>
About the test piece which performed the 90 degree W bending process based on JISH3130 (2012), bending cross section was observed using KEYENCE Corporation microscope VW-6000, and bending angle (theta) (deg) was measured. The difference θ-90 ° between this bending angle and the bending angle (= 90 °) when loaded with a mold was taken as the springback angle Δθ (deg).

As shown in Tables 1 and 2, in each of Inventive Examples 1 to 17, 0.2% proof stress in the rolling parallel direction was obtained by performing homogenization annealing, hot rolling, solution treatment and the like under predetermined conditions. It became 550 MPa or more, the conductivity was 55% IACS or more, and further, S = S ₂₁ / (S ₁ + S ₃₆ ) ≧ 0.5. Moreover, favorable bending process outer peripheral surface roughness Ra and spring back angle (DELTA) (theta) were able to be obtained.

In Comparative Example 1, since the strain rate of hot rolling is too small, S = S ₂₁ / (S ₁ + S ₃₆ ) becomes small, and the outer peripheral surface roughness Ra and the springback angle Δθ of the bent portion deteriorate.
In Comparative Example 2, since the strain rate of hot rolling was too large, cracking occurred in the hot rolling, and a product could not be obtained.
In Comparative Example 3, coarse Co-Si particles can not be solid-solved in the matrix because the temperature in the homogenization treatment is too low, and S = S ₂₁ / (S ₁ + S ₃₆ ) decreases. The 0.2% proof stress, the outer circumferential surface roughness Ra of the bent portion and the spring back angle Δθ deteriorated.
In Comparative Example 4, since the temperature in the homogenization treatment is too high, the crystal grains after hot rolling become coarse, S = S ₂₁ / (S ₁ + S ₃₆ ) becomes small, and the outer peripheral surface of the bent portion is roughened. And the springback angle .DELTA..theta.
In Comparative Example 5, since the cooling rate after the hot treatment was too slow, coarse Co-Si particles were precipitated, and S = S ₂₁ / (S ₁ + S ₃₆ ) became small, and 0.2% proof stress And the bending part outer peripheral surface roughness Ra deteriorated.
In Comparative Example 6, since the temperature in the solution treatment was too high, the 0.2% proof stress deteriorated, and S = S ₂₁ / (S ₁ + S ₃₆ ) decreased, and the springback angle Δθ deteriorated.
In Comparative Example 7, since the temperature in the solution treatment was too low, the 0.2% proof stress deteriorated, and S = S ₂₁ / (S ₁ + S ₃₆ ) decreased, and the outer peripheral surface roughness Ra of the bent portion deteriorated. did.
In Comparative Examples 8 and 9, when the amount of Co deviated from the predetermined range, the 0.2% proof stress, the conductivity, and the outer peripheral surface roughness Ra of the bending portion deteriorated.
In Comparative Examples 10 and 11, 0.2% proof stress or conductivity decreased due to Co / Si being out of the predetermined range by mass ratio.

  As described above, according to the present invention, a copper alloy for electronic materials with high reliability, which has 0.2% proof stress, conductivity and bending workability suitable for use in electronic materials and which suppresses springback during bending. Was found to be obtained.

Claims (6)

EBSD (Electron Back Scatter) containing 0.5 to 3.0% by mass of Co, and containing Si in a mass ratio so that Co / Si is 3 to 5 with the balance being copper and unavoidable impurities Box numbers 1, 21 obtained by performing equal area division used in vector method display on stereo triangles representing crystal orientations in the rolling parallel direction (RD) obtained from Diffraction (electron backscattering diffraction) measurement Assuming that the degree of integration of the 36 crystal orientations is S ₁ , S ₂₁ and S ₃₆ respectively,
S = S ₂₁ / (S ₁ + S ₃₆ ) ≧ 0.5
Copper alloys for electronic materials that satisfy the relationship of   Assuming that the actual bending deformation angle of the bending portion (central portion among the three portions) in the bending test piece is θ (°) in a 90 ° W bending test based on JIS H 3130 (2012), the spring back amount Δθ is The copper alloy for electronic materials according to claim 1, wherein the value of θ−90 ° is 5 ° or less.   In the 90 ° W bending test in accordance with JIS H 3130 (2012), the surface average roughness Ra in accordance with JIS B 0601 (2013) on the outer peripheral surface of the bending portion (central portion among three points) in the bending test piece is 1. The copper alloy for electronic materials according to claim 1 or 2, which is 0 μm or less.   Furthermore, the copper alloy for electronic materials as described in any one of Claims 1-3 which contain Cr by 0.5 mass% or less.   Furthermore, each of Zn and Sn is contained at 0.5 mass% or less, Ni at 0.1 mass% or less, Mg, Mn, Fe, Ti, Al, P and B at 0.2 mass% or less, The copper alloy for electronic materials according to any one of claims 1 to 4, wherein a total of at least one selected from Sn, Ni, Mg, Mn, Fe, Ti, Al, P and B is 1.0 mass% or less. .   The electronic component provided with the copper alloy for electronic materials as described in any one of Claims 1-5.